Rats overrun Dokdo, posing dire threat to fragile ecosystem

Social Affairs

Published: 21 May. 2024, 13:53 Updated: 22 May. 2024, 17:48

Rats overrun Dokdo, posing dire threat to fragile ecosystem

A brown rat is trapped inside a trap on the Dokdo islets. [CHO YOUNG-SEOK]

Rats are taking over the Dokdo islets in the East Sea, prompting the Environment Ministry to take action.

The rapidly growing rat population not only poses a threat to the islets’ ecosystem but also causes damage to Dokdo's facilities.

“Rats from outside Dokdo have been discovered on the easternmost Dokdo islets,” the Ministry of Environment said on Sunday.

Genetic testing confirmed them as brown rats, also known as Rattus norvegicus, the most common rat species in Korea.

The Environment Ministry plans to investigate the current rat population on the Dokdo islets and eradicate them by May next year.

A brown rat moves around a trap set to be installed in the Dokdo islets. [CHO YOUNG-SEOK]

Ecologists, along with the Daegu Regional Environmental Office, Gyeongbuk Provincial Police and Ulleung County Office, will visit the Dokdo islets at the end of this month to assess the situation.

They will deploy specially designed traps to catch the rats.

“Rat poison can cause collateral damage to other living things on the islets, so we will use traps targeting the rats’ heads to catch them,” said Cho Young-seok, a professor at the Department of Biology Education at Daegu University.

“We are testing if we can exclusively target rats without catching other animals.”

Rats were not originally inhabitants of the Dokdo islets. Their presence was first discovered in 2010 on Seodo, the west islet, and later in 2015 on Dongdo, the east islet.

With no natural predators on the island, their population has skyrocketed. It was estimated at 100 to 150 in 2021 and is likely much higher now due to their rapid reproduction rates and their status as the only mammals on the islets.

A screen capture of CCTV footage showing a brown rat on the Dokdo islets. [CHO YOUNG-SEOK]

The proliferation of brown rats has become a pressing concern due to their detrimental impact on the island's ecosystem and infrastructure.

Feeding on birds, rice and plants, they disrupt the natural balance, and they also damage the electric wires installed on the island, affecting essential facilities, including the Dokdo Security Police station and the lighthouse.

Kim Yoon-bae, head of the Ulleungdo Dokdo Ocean Research Station at the Korea Institute of Ocean Science and Technology, expressed concern over the challenges field workers face due to rat-induced damages and pledged to “actively support research efforts aimed at addressing the growing rat population on the Dokdo islets.”

The Environment Ministry plans to analyze how the rats entered the islets to prevent their further entrance.

It is uncertain how the rats reached the Dokdo islets, located around 200 kilometers (124 miles) from the closest land, Uljin District in North Gyeongsang. However, the dominant view is that they accessed the islets via boats traveling to and from the island.

“The brown rats most probably arrived on the Dokdo islets through cargo ships transporting food and raw materials, rather than passenger ships,” Prof. Cho said.

Genetic analysis conducted by Professor Cho’s research team further indicates a close relationship between the rats on Dokdo and those on Ulleung Island.

Visitors take photos of the Dokdo islets in a passenger ship that heads to the Dokdo islets. [NEWS1]

Rats are not the first mammals to occupy the islets.

In 1973, police released 40 rabbits on the islets as a food supply source. This later became a problem as their numbers soared to 230.

Ulleung County began eradicating them in 1988, successfully eliminating them within four years.

Experts believe that removing rats from the Dokdo islets may not be overly challenging given the small size of the islets.

Cho said that rather than attempting a one-time eradication effort, it would be more feasible to catch them while experts reside on the islets for an extended period.

BY CHUN KWON-PIL, WOO JI-WON [woo.jiwon@joongang.co.kr]